Once again, splitting hairs there Car RAMROD, "Should" implies that it's something you "Should" do, you do have a choice not to but should you come unstuck as a result of that information it would come back to that little disclaimer and you'd be told by BOM "Not our fault, you SHOULD have used ASA, too bad"
We all know it comes down to the legalese, if the information there wasn't up-to-date or someone hadn't bothered because it's not strictly meant for Flight Planning and you went ahead and used it not knowing there had been a change and it caused a problem it'd be the perfect loop-hole for CASA and/or your Insurance people to put the blame on you.
It's their way of saying "We put it up, but we might not necessarily keep it up to date, that's not really our job to provide for the public in such a manner, but here it is anyway and a disclaimer so that if we forget or don't keep it up to date we're not liable". ASA have a strict requirement for their information to be up to date, it's what we use for Flight Planning, if you got your info there and as a result came unstuck you'd be perfectly covered because that's what it's intention is for. Use the BOM stuff at your own risk though.
Of course, as Lead Sled already said, if you really want to go ahead and use it and it all comes undone, feel free to take it to court and see how it works out, my guess is you'll walk back out with a much smaller bank account and nothing to show for it.